Ruud PROUH40 T2 CD400-SO

It holds 36 gallons in the test, 4 gallons less than its 40-gallon sold size. Over one hour from a full tank, it gave 60 gallons in the test (its first-hour rating). That is 24 gallons more than its tank holds, since it reheats during the hour. In the first hour, 371 of the 481 heat pump models give more hot water. The median heat pump model gives 72 gallons in the first hour of the test.

The single model number sold under it is ENERGY STAR certified. In the test, it delivered 3.83 units of hot water energy for each unit used (its UEF). It moves heat from the air rather than making it, so its UEF passes 1. In the test, daily hot water use was set to medium (its draw pattern). Of 226 heat pump models with the same draw pattern, 23 have a higher UEF and 172 a lower one. For its type and draw pattern, the median UEF is 3.68. When it reheats water in the test, the water gains 434% of the energy it uses.

There are 28 more basic models with the same test figures. Of those, one or more are under the Friedrich, Rheem, and Richmond brands. For the full group, see the Rheem PROPH40 T2 RH375-SO.

It may qualify for 21 rebate programs in 20 states. Another 7 programs may accept it if it meets their other terms.